Welded terminal resistor



' Jan. 11,1966 F. l. ELLlN 3,229,238

WELDED TERMINAL RESISTOR Original Filed Feb. 2. 1950 resistors of theforegoing type. the'resistors to glaze the enamel, the terminal lugs areincidentally oxidized, and sometimes burned. Accordingly, theterminallugs must be cleaned and tinned before installed. "siderableskill and precision to avoid damaging the glazed United States Patent3,229,238 WELDED TERMINAL RESISTOR Fredrick I. Elihu, Skokie, Illassignor, by mesne assignments, to Consolidated Electronics IndustriesCorp., New York, N.Y., a corporation of Delaware Division of applicationSer. No. 142,070, Feb. 2, 1950,

now Platent No. 2,675,453, dated Apr. 13, 1954. Continllat on ofabandoned application Ser. No. 403,484, Jan. 12, 1954. This applicationFeb. 29, 1960, Ser. No. 11,745

8 Claims. '(Cl. 338329) This invention is concerned generally withresistors and likeelectrical elements, and more particularly with animproved wire-wound resistor as an article of manufacture. Thisapplication comprises a division of my application Apparatus forManufacture ofWelded Termiwinding resistance wire on a ceramic core. Theends of the wire are welded or otherwise electrically and mechanicallysecured to metallic bands encircling the core near the ends thereof.Each band conventionally comprises a strip of sheet metal bent aroundthe core with the ends extending radially outwardly in the samedirection from the core-arid'welded or otherwise secured together toform aterminal log for mounting the resistor and for making electricalconnections thereto. The wiregenerally is bare, and atbest may beprotected by a rather delicate coating of insulation. As a result, thewire is readily susceptible to physical damage and short circuits. Toguard against this, the wire, core, and the bands exclusive of theoutermost projecting ends thereof are genjerallycoated' with a vitreousenamel. The resistor is then fired to glaze the enamel.

Certain difficulties are encountered in manufacturing In the process offiring lead 'wires can be soldered to them when the resistor is Cleaningof the terminal lugs requires convitreous coating. Furthermore,conventional means or methods of cleaning metal surfaces, insofar asthey can 'be applied to electrical resistors and the like, tend to leaveareas which are not quite clean, or which are susceptible to'corrosion.This leads to imperfect bonding and eventually to poor electricalcontact.

Toxprevent cracking of the core or the glazed vitrified coating, and toprevent loosening of the terminal bands,

Ice

as terminals. It is apparent that different sizes of resistors requiredifferent lengths of hands. When the lugs are integral with the bands inaccordance with conventional practice, a large number of sizes ofintegral bands and lugs must be kept on hand. This number is furtherincreased when it is considered that many different types and shapes ofmounting lugs are required for different installations.

It is an object of this invention to obviate all of the above enumeratedfaults and others by providing a resistor with terminal bands havingonly short integral projections extending therefrom and a terminal lugor tab welded to each projection. v

More specifically, it is an object of this invention to provide aresistor having a terminal band wherein a terminal lug or tab is buttwelded to a short integral projection of the band.

A further object of this invention is to provide a resister or the likehaving a coating stabilized by heat wherein projecting conductingmembers are instantly oxidized during stabilization of such coating bythe application of heat wherein the projections are clipped off toprovide clean surfaces and electrical terminals are welded onto theclipped, clean surfaces.

Other and further objects and advantages will be apparent from thefollowing description when taken in connection with the accompanyingdrawings wherein:

FIG. 1 is a perspective view of a resistor constructed in accordancewith the principles of this invention prior to the welding of theterminal lugs thereon, the vitreous enamel coating being omitted forclarity of illustration;

FIG. 2 is a viewsimilar to FIG. 1 after the terminal lugs or tabs havebeen welded on;

FIG. 3 is a cross-sectional view taken substantially along the line 33of FIG. 2, the vitreous enamel being shown;

FIG. 4 is a fragmentary view of a resistor showing a different type ofterminal lug or tab;

FIG. 5 is a view similar to FIG. 4 showing another type of tab or lug;

FIG. 6 is a sectional view of a resistor and the jaws for clamping theterminal band extension and the terminal lug prior to welding thereof;and

FIG. 7 is a view similar to FIG. 6 taken as the terminal lug or tab isbeing welded to the band projection.

Attention first is invited to FIGS. 1-3 for an understanding of theinvention. The resistor, generally identified by thenumeral 10,comprises a ceramic core 12 on which is wound a wire resistance element14. The wire is welded or otherwise secure-d at both ends toterminalbands 16 and 18 as indicated at 20. The bands comprise strips of sheetmetal which are bent around the core to conform closely therewith, andwhich have upstanding,

integral extensions or projections 22 and 24, these projectionscomprising the ends of the bands bent upwardly and spot welded togetheras indicated at 26 in'FIG. 3.

The resistor is shown in, FIG. 1 before welding of the terminal lugs ortabs thereon, and it will be appreciated that the outer ends of theprojections 22 and 24 are clipped off after'firing of the enamel topresent clean welding surfaces 28 and 30. The terminal lugs or tabs 32and 34 are illustrated in FIG. 1 before attachment to the integral tabsor lugs. The completed resistor is shown in FIG. 2 with the tabs or lugsrespectively butt welded to the clean welding surfaces 28 and 30respective- 1y. The tabs or lugs 32 and 34 are respectively providedwith apertures 36 and 38 for receipt of terminal wires. Across-sectional view of the entire resistor is shown in FIG. 3 includingthe glazed vitreous coating 389 thereon, this coating preferably beingof vitreous enamel, but it will be understood that the coating could beof any other suitable or known material, particularly such a material asmight be stabilized by the application of heat.

A fragment of a resistor similar to that previously described is shownin FIG. 4, this resistor and the parts thereof being identified bynumerals previously utilized with the addition of a suifix a. Theresistor 10a again comprises a ceramic core 12a and a wire resistorelement 14a wound on the core, Only one of the terminal bands 16a isillustrated with the wire connection 20a thereon. The integralprojection 22a remains as before. However, in this resistor a terminallug or tab 32a of somewhat different configuration and having anaperture 36a therein is butt welded onto the clean, clipped end of theprojection 22a. The lug or tab 32a is illustrated as being larger thanin the previous embodiment, and it may also be of different material.

A further modification of the invention is illustrated in FIG. 5. Inthis figure the parts are generally similar to those previouslydisclosed, and are identified by similar numerals with the addition ofthe suffix b. Further description therefore is believed to beunnecessary except for terminal lugor tab 32b. In this instance theterminal lug or tab 32b is L-shaped, having a shank portion 40 which isbutt welded to the clean, clipped end of the projection 22b, and alsohaving a laterally projecting foot 42 in which there is located anaperture 36b. It will be evident upon inspection of FIG. that the tab orlug shown therein is adapted for installations of different types thanthose previously illustrated.

The manner in which the terminal lugs or tabs are welded on theprojections 22 is illustrated in FIGS. 6 and 7. The welding isillustrated with regard to the resistor embodiment first disclosed. Thesame numerals are used as were used originally, and repetition of thedescription is unnecessary. A stud or arbor 44 projects through thecenter of the ceramic core 12 to support the resistor with the integralprojection 22 thereon extending downwardly between a pair of jaws 46 and48, the former of which has a positioning lug or tooth 50 projectinginto a complementary recess in the opposite jaw 48 to provide forpositioning of the projection 22. It will be noted that the jaw wherethey engage the projection 22 are rather thin in a vertical directionfor providing proper clearance. A pair of terminal lug or tab clampingjaws 52 is positioned beneath the previously noted jaws 46 and 48, andcomprises a left-hand jaw 54 having a recess 56 therein for receipt ofone of the tabs or lugs, as 32. The right-hand or opposed jaw 58 isprovided with a block or tooth 60 adapted to project into the recess 56for clamping the terminal lug or tab therein. As will be apparent inFIG. 7 the jaws 46 and 48 are brought toward one another to clamp theprojection 22, while the jaws 54 and 58 move toward one another to clampthe terminal lug or tab 32. The two sets of jaws and the arbor 44 thenare relatively moved toward one another to butt the terminal lug or tabagainst the projection 22, and welding current is applied throughsuitable connections (not shown) to the jaws to weld the tab or lug onthe projection.

It will be apparent that the resistor herein disclosed may be moreeconomically manufactured than those previously known in the artinasmuch as only one size, or at most very few sizes, of terminal bandneed be kept on hand, yet a practically infinite number of terminal lugsor hands of various sizes, shapes and consistencies may be applied. Thewelded on lugs are never oxidized by the firing of the vitreous enamelcoating, and therefore need not be cleaned. The clipped off ends of theintegral band projections are absolutely clean so that the lugs or tabsreadily can be butt welded thereon.

Although the invention has been illustrated specifically with regard toa resistor, it is contemplated that other types of electrical elementsmight have terminals similar to the novel terminals herein disclosed. Itis to be understood that the specific examples herein shown anddescribed are by way of illustration only. Various structural changesare possible and constitute a part of this invention insofar as theyfall within the spirit and scope of the appended claims.

Iclaim:

1. A resistor comprising a core, an elongated resistive element wound onsaid core, a metal band on one end of said core electrically connectedto said resistive .-ele.- ment and having a standard size relativelyshort adaptor portion extending away from said core whereby to adapt theresistor to the attachment of various types of terminals, a coating ofheat-stabilized insulating material on said core, resistive element andband; the outer end of said relatively short adaptor portion being freeof said coating and oxidation incident to heat-stabilization thereof,and a terminal having an oxide-free end separately butt welded to theoxide-free outer end of said relatively short portion to present a leadwire attachment portion projecting beyond the adaptor portion.

2. An electrical element comprising an insulating base, impedance meansdisposed on said base, a substantially uniform conductive band wounduniformly about said base and having the ends thereof joined togetherand projecting outwardly a relatively short distance from said base toprovide an adaptor portion presenting a double wall thickness of theband material for the attachment of various types of terminals, saidband being in electrical contact with said impedance means, and aterminal having an oxide-free end separately butt welded to the doublewall thickness of the projecting ends of said band .to present a leadwire attachment portion projecting beyond the adaptor portion; saidbase, impedance means and band being covered by a heat-stabilizedinsulating material with the projecting ends of said band being free ofsaid insulating material and of oxidation attendant upon heatstabilization thereof facilitating attachment of the terminal thereto.

3. An electrical element as claimed in claim 2, wherein the projectingends of the band are welded together closely adjacent the coating withthe free ends thereof clipped to present clean surfaces for attachmentof the terminal thereto.

4. The method of manufacturing resistors of the type including a coreand an elongated resistive element wound thereon; which method comprisesapplying a metal band to one end of the said core in electricalconnection with the resistive element and with a relatively shortprojecting portion of said band extending outwardly from the coreproviding an adaptor portion permitting attachment thereto of varioustypes of terminals, coating the core, the resistive element thereon, andthe band within the outer end of the projecting portion of the band withan insulation material, firing the insulation on the resistor withincidental oxidation of the projecting portion of the band, removing theoxide coating from the outer end of the projecting portion of the bandto expose a clean metallic surface free of the effect of oxidationresulting from firing of the insulation, and welding an oxide-free endof a'terminal to the clipped clean metallic surface of the projectingportion of the band to elongate the projecting portion and provide alead wire attachment terminal free from oxidation incident to firing ofthe insulation on the resistor.

5. The method of manufacturing resistors of the type including a coreand an elongated resistive element wound thereon;-which method comprisesapplying a metal band to one end of the said core in electricalconnection with the resistive element and with a relatively shortprojecting portion of said band extending outwardly from the coreproviding an adaptor portion permitting attachment thereto of varioustypes of terminals, coating the core, the resistive element thereon, andthe band within the outer end of the projecting portion of the band withan insulation material, firing the insulation on the resistor withincidental oxidation of the projecting portion of the band, clipping theouter end of they projecting portion of the band to expose a cleanmetallic surface free of the eficct of oxidation resulting from firingof the insulation, and welding an oxide-free end of a terminal to theclipped clean metallic surface of the projecting portion of the band toelongate the projecting portion and provide a lead wire attachmentterminal free from oxidation incident to firing of the insulation on theresistor.

6. The method of manufacturing resistors of the type including a coreand an elongated resistive element wound thereon; which method comprisesapplying a metal band to one end of the core in electrical connectionwith the resistive element and with relatively short extremities of theband extending outwardly from the core in abutting relation to form arelatively short projecting portion providing an adaptor portionpermitting attachment thereto of various types of terminals, weldingtogether the abutting extremities of the band relatively close to thecore, coating the core, the resistive element thereon, and the bandwithin the outer end of the projecting portion of the band with aninsulation material, firing the insulation on the resistor withincidental oxidizing of the projecting portion of the band, clipping theouter ends of the extremities of the projecting portion of the bandexteriorly of the Welded connection between said extremities to expose aclean metallic surface free of the effect of oxidation resulting fromfiring of the insulation, and welding an oxide-free end of a terminal tothe clipped clean metallic surface of the projecting portion of the bandto elongate the projecting portion and provide a lead wire attachmentterminal free from oxidation incident to firing of the insulation on theresistor.

7. The method of claim 4, wherein the short projecting portion of theband serves as a surface to be gripped in supporting the resistor forattachment of the terminal thereto.

8. An electrical element as claimed in claim 3, wherein the separatelyattached terminal is of a single thickness of material with the doublewall thickness of the projecting ends providing a relatively wide baseportion for butt welding of the terminal thereto.

References Cited by the Examiner UNITED STATES PATENTS 1,830,084 11/1931Bjornd-al 29155.69 1,932,923 10/ 1933 Bullin-ger 338329 2,043,196 6/1936 Finlayson 29-15569 2,402,122 6/1946 Bullinger 29-155.71 2,413,04312/ 1946 Ganc-i 338329 2,636,963 4/1956 Wakefield 33 8-329 2,666,120'1/19'54 Chanowitz 338--329 2,667,606 1/1954 Rood et al 33927 52,675,453 4/ 4 El-lin 219101 2,739,212 3/19'56 Woolley et a] 29-155692,820,076 1/195'8 Lillienberg 338329 RICHARD M. WOOD, Primary Examiner.

R. K. WINDHAM, Examiner.

1. A RESISTOR COMPRISING A CORE, AN ELONGATED RESISTIVE ELEMENT WOUND ONSAID CORE, A METAL BAND ON ONE END OF SAID CORE ELECTRICALLY CONNECTEDTO SAID RESISTIVE ELEMENT AND HAVING A STANDARD SIZE RELATIVELY SHORTADAPTOR PORTION EXTENDING AWAY FROM SAID CORE WHEREBY TO ADAPT THERESISTOR TO THE ATTACHMENT OF VARIOUS TYPES OF TERMINALS, A COATING OFHEAT-STABILIZED INSULATING MATERIAL ON SAID CORE, RESISTIVE ELEMENT ANDBAND; THE OUTER END OF SAID RELATIVELY SHORT ADAPTOR PORTION BEING FREEOF SAID COATING AND OXIDATION INCIDENT TO HEAT-STABILIZATION THEREOF,AND A TERMINAL HAVING AN OXIDE-FREE END SEPARATELY BUTT WELDED TO THEOXIDE-FREE OUTER END OF SAID RELATIVELY SHORT PORTION TO PRESENT A LEADWIRE ATTACHMENT PORTION PROJECTING BEYOND THE ADAPTOR PORTION.